Future Perfect Continuous Tense emphasizes the duration of an activity that will be in progress before another time or event in the future.
(+) S + SHALL/WILL + HAVE + BEEN + V-ING + O
(- ) S + SHALL/WILL + NOT + HAVE + BEEN + V-ING + O
(?) SHALL/WILL + S + HAVE + BEEN + V-ING + O
USE 1 Duration Before Something in the Future
We use the Future Perfect Continuous to show that something will continue up until a particular event or time in the future. “For five minutes,” “for two weeks,” and “since Friday” are all durations which can be used with the Future Perfect Continuous. Notice that this is related to the Present Perfect Continuous and the Past Perfect Continuous; however, with Future Perfect Continuous, the duration stops at or before a reference point in the future.
• They will have been talking for over an hour by the time Thomas arrives.
• She is going to have been working at that company for three years when it finally closes.
• James will have been teaching at the university for more than a year by the time he leaves for Asia.
• How long will you have been studying when you graduate?
Notice in the examples above that the reference points (marked in italics) are in Simple Present rather than Simple Future. This is because these future events are in time clauses and you cannot use future tenses in time clauses.
USE 2 Cause of Something in the Future
Using the Future Perfect Continuous before another action in the future is a good way to show cause and effect.
• Jason will be tired when he gets home because he will have been jogging for over an hour.
• Claudia’s English will be perfect when she returns to Germany because she is going to have been studying English in the United States for over two years.
Future Continuous vs. Future Perfect Continuous
If you do not include a duration such as “for five minutes,” “for two weeks” or “since Friday,” many English speakers choose to use the Future Continuous rather than the Future Perfect Continuous. Be careful because this can change the meaning of the sentence. Future Continuous emphasizes interrupted actions, whereas Future Perfect Continuous emphasizes a duration of time before something in the future. Study the examples below to understand the difference.
• He will be tired because he will be exercising so hard.
This sentence emphasizes that he will be tired because he will be exercising at that exact moment in the future.
• He will be tired because he will have been exercising so hard.
This sentence emphasizes that he will be tired because he will have been exercising for a period of time. It is possible that he will still be exercising at that moment OR that he will just have finished.
REMEMBER No Future in Time Clauses
Like all future forms, the Future Perfect Continuous cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of Future Perfect Continuous,Present Perfect Continuous is used.
• You won’t get a promotion until you will have been working here as long as Tim. Not Correct
• You won’t get a promotion until you have been working here as long as Tim. Correct
AND REMEMBER Non-Continuous Verbs / Mixed Verbs
It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Future Perfect Continuous with these verbs, you must use Future Perfect.
• Ned will have been having his driver’s license for over two years. Not Correct
• Ned will have had his driver’s license for over two years. Correct
• Change the following sentences into positive, Negative, and Interrogative forms of future Perfect Continuous Tense.
1. All the ministers (start) the cabinet meeting for one hour by the time the President and Vice President arrive at eleven o’clock next Thursday.
2. The students (discuss) their exercises by the time the teacher arrives in the classroom at eight o’clock tomorrow morning.
3. The Christian people (pray) at the church by December 25 next year.
4. The red cross organization of Indonesia (begin) the conference for thirty minutes by the time the President officially open it at 10.00 a.m tomorrow.
5. By the end of this month the people’s consultative assembly (complete) their special session.
• Complete this sentence with the future perfect continuous tense.
1. In three years’ time I (study) English for 20 years.
2. If you are 20 years old, it means that you (live) fo 20 years.
3. When we arrive in Surabaya, we (travel) for 22 years.
4. By this time next week I (stay) here for 2 weeks.
5. By the end of this semester we (see) each other for 6 months.